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module Mirage_protocol : sig ... end
The type for flows. A flow represents the state of a single reliable stream stream that is connected to an endpoint.
include Mirage_flow.S
with type flow := flow
and type error = [ `Msg of string | `Not_found | `Cycle ]
The type for write errors.
val pp_write_error : write_error Fmt.t
pp_write_error
is the pretty-printer for write errors.
read flow
blocks until some data is available and returns a fresh buffer containing it.
The returned buffer will be of a size convenient to the flow implementation, but will always have at least 1 byte.
When read
returns `Eof
or an error, close
(or shutdown
) should be called on the flow
by the client. Once read
returned `Eof
or an error, no subsequent read
call will be successful.
val write : flow -> Cstruct.t -> (unit, write_error) result Lwt.t
write flow buffer
writes a buffer to the flow. There is no indication when the buffer has actually been sent and, therefore, it must not be reused. The contents may be transmitted in separate packets, depending on the underlying transport. The result Ok ()
indicates success, Error `Closed
indicates that the connection is now closed and therefore the data could not be written. Other errors are possible.
The promise is resolved when the buffer has been accepted by the implementation (if a partial write occured, write
will wait until the remainder of the buffer has been accepted by the implementation).
If write
returns an error, close
(or shutdown
) should be called on the flow
by the client. Once write
returned an error, no subsequent write
or writev
call will be successful.
val writev : flow -> Cstruct.t list -> (unit, write_error) result Lwt.t
writev flow buffers
writes a sequence of buffers to the flow. There is no indication when the buffers have actually been sent and, therefore, they must not be reused. The result Ok ()
indicates success, Error `Closed
indicates that the connection is now closed and therefore the data could not be written. Other errors are possible.
The promise is resolved when the buffers have been accepted by the implementation (if a partial write occured, writev
will wait until all buffers have been accepted by the implementation).
If writev
returns an error, close
(or shutdown
) should be called on the flow
by the client. Once writev
returned an error, no subsequent writev
or write
call will be successful.
shutdown flow mode
shuts down the flow
for the specific mode
: A flow which is shutdown `read
(or `read_write
) will never be read
again (subsequent calls will return `Eof
); a flow which is shutdown `write
(or `read_write
) flushes all pending writes and signals the remote endpoint there won't be any future write
or writev
calls (subsequent calls will return `Closed
). E.g. in TCP, the signalling is done by sending a segment with the FIN flag.
If this flow
is layered upon another flow'
(e.g. TLS over TCP), and the internal state after shutdown
is `Closed
, close
on the underlying flow'
is executed.
close flow
terminates the flow
and frees all associated data. Any subsequent read
or write
will return an error. A subsequent close
will not do anything (esp. not raising an exception), but it may log an error.
If this flow
is layered upon another flow'
(e.g. TLS over TCP), close
on the underlying flow'
is executed.
module Fun : sig ... end
val make : name:string -> 'edn value
make ~name
is a new witness.
replace w v ctx
replaces the value of w
by v
if it exists or bound w
to v
.
val empty : ctx
empty
is the empty context.
val register :
?priority:int ->
name:string ->
(module Mirage_protocol.S with type endpoint = 'edn and type flow = 'flow) ->
'edn value * ('edn, 'flow) protocol
register ?priority ~name (module Protocol)
registers the given Protocol
into the internal global Mimic's state as a possible transmission protocol available via resolve
.
?priority
is used to help mimic to choose between multiple solutions according to the given context. Mimic will choose the lower-priority solution.
name
helps the end-user to know which solution mimic will dynamically via log outputs.
register
returns 2 values:
module type REPR = sig ... end
repr protocol
gives a module definition with an OCaml constructor to help the end-user to destruct the structural type of a given flow
:
module Protocol
: Mirage_protocol.S with type flow = Lwt_unix.file_descr
let edn, protocol = Mimic.register ~name:"protocol" (module Protocol)
module R = (val (Mimic.repr protocol))
let () = Mimic.resolve ~ctx >>= function
| Ok (R.T lwt_unix_file_descr) -> ...
| ...
resolve ctx
tries to instantiate a flow
from the given ctx
.
equal a b
returns a proof that a
and b
are structurally equal.
unfold ctx
applies any functions available into the given ctx
and and possible to compute according to available values and return a list of what these functions return.
It's useful to do an introspection of what mimic
does when it resolve
s the given ctx
. From that and equal
, the user is able to introspect what mimic
generated and which protocol it is able to instantiate then.
al:resolve} is: {[ let resolve ctx = unfold ctx >>= function | Ok lst -> connect lst | Error _ as err -> Lwt.return err ]}